[llvm] [RISCV][TTI] Return invalid for getCastInstrCost w/vector split. (PR #221913)

[via llvm-commits]

github-actions[bot] wrote:

test-suite diff from 4b11439e535eb820d2f4cc5ac9694bf539d8213f...f0ff52f2b2211e88f9000885dc66f3e50bee8a71: https://github.com/llvm/llvm-project/actions/runs/34219904175/artifacts/10056758081

Statistics: https://github.com/llvm/llvm-project/actions/runs/34219904175/artifacts/10056758902

## riscv64-linux-gnu `-march=rva23u64 -O3`
| ('Program', '')    |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:-------------------|-------------------------:|-------------------------:|-------------------------:|
| Geomean difference |                      nan |                      nan |             -5.37274e-06 |
## aarch64-linux-gnu `-march=armv9-a -O3`
| ('Program', '')    |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:-------------------|-------------------------:|-------------------------:|-------------------------:|
| Geomean difference |                      nan |                      nan |                        0 |
## x86_64-linux-gnu `-march=x86-64-v3 -O3`
| ('Program', '')    |   ('size..text', 'base') |   ('size..text', 'head') |   ('size..text', 'diff') |
|:-------------------|-------------------------:|-------------------------:|-------------------------:|
| Geomean difference |                      nan |                      nan |                        0 |


https://github.com/llvm/llvm-project/pull/221913